athodic Polarization Characteristics of La_0.5Sr_0.5CoO₃ and Ag Electrodes with the (Bi₂O₃ )_0.77(Y₂O₃)_0.23 Film Electrolyte

Abstract

The electrode behavior of Lao., La_0.5Sr_0.5CoO₃ and Ag electrodes on (Bi₂O₃ )_0.77(Y₂O₃)_0.23 film solid electrolytes were investigated by means of d. c. and a. c. measurements at the temperature range of 200∼500°C under N₂-20% O₂ gas mixture. The electrolyte polarization or iR drop can be distinguished from the electrode polarization using a a. c. method or a current interruption method with the aid of a reference electrode.
(Bi₂O₃)_0.77(Y₂O₃)_0.23 film solid electro lytes were prepared by the thermal decomposition method employing the ultrasonic technique and by the rf magnetron sputtering method. Both of these film electrolytes had noncrystalline bulk structure, but the sintered disk electrolyte had polycrystalline.
The electrode process is strongly influenced by the nature of the electrode/electrolyte interface. The d. c. and a. c. polarization properties for the La_0.5Sr_0.5CoO₃ electrode on the film electrolyte prepared by the thermal decomposition method were more favourable than those of the other electrode/film electrolyte systems.
On the La_0.5Sr_0.5CoO₃/film electrolyte prepared by the thermal decomposition method, the diffusion resistance of the reaction species along the interface plays an important role in determining the electrode kinetics. On the other hand, on the La_0.5Sr_0.5CoO₃/film electrolyte prepared by the rf magnetron sputtering method, another process, probably the diffusion of electronic species in the electrolyte is dominant.